Production of highly crimped polyester yarn

ABSTRACT

Polyester yarn which develops good crimp under load for singleor double-knit or woven fabrics is produced from drawn multifilament yarn by passing the filaments over an unheated nonmetallic pin at high speed to modify the filaments frictionally on one side, forwarding the filaments in a jetted stream of heated compressible fluid, impinging the filaments in a plasticized condition against a moving screen, cooling the filaments and then taking up the filaments from the screen. Exemplified products have a crimp development of at least 10 percent under 0.5 milligram per denier load and an average crimp frequency greater than 30 crimps per extended inch of filament; the crimped yarns have a random three-dimensional, curvilinear crimp along the filaments and are free from twist liveliness.

Frankfort et al.

[451 Jan. 21, 1975 PRODUCTION OF HIGHLY CRIMPED POLYESTER YARN lnventors: Hans R. E. Frankfort, Kinston,

NC; Peter F. Lyons, Wilmington, Del.

E. l. du Pont de Nemours & C0,, Wilmington, Del.

Filed: Aug. 18, 1972 Appl. No.: 281,972

Related U.S. Application Data Continuation-impart of Ser. No. 210,884, Dec. 22, 1971, abandoned.

Assignee:

U.S. C1. 57/140 R, 28/72.12, 57/157 F Int. Cl D02g 1/16, D02g 3/24 Field of Search 57/140 R, 140 B, 34 B, 57/157 F, 157 R;28/1.3, 1.4, 72.17, 72.12, 72.11, 72.13; 264/168 References Cited UNITED STATES PATENTS 3,379,809 4/1968 3,601,872 8/1971 Potman et al 28/12 Primary Examiner-John Petrakes [57] ABSTRACT Polyester yarn which develops good crimp under load for singleor double-knit or woven fabrics is produced from drawn multifilament yarn by passing the filaments over an unheated nonmetallic pin at high speed to modify the filaments frictionally on one side, forwarding the filaments in a jetted stream of heated compressible fluid, impinging the filaments in a plasticized condition against a moving screen, cooling the filaments and then taking up the filaments from the screen. Exemplified products have a crimp develop ment of at least 10 percent under 0.5 milligram per denier load and an average crimp frequency greater than 30 crimps per extended inch of filament; the crimped yarns have a random three-dimensional, curvilinear crimp along the filaments and are free from twist liveliness.

14 Claims, 12 Drawing Figures PATENTEB JAN 21 I975 snaznor 4 FIG.

PATENTED W21 3.86 1,1 33

sum 3 or 4 Fla YARN

PATENTEfl- I975 3,861 11313 SHEET u 0F 4 new: F|G.7B FIG JG F|G.7D FIG I CENTIMETER I CEITIIETER PRODUCTION OF HIGHLY CRIMPED POLYESTER YARN REFERENCE TO RELATED APPLICATION This is a continuation-in-part of our copending application Ser. No. 210,884 filed Dec. 22, 1971, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a high speed process for texturing multifilament polyester yarn, and to the textured products suitable for woven and knit fabrics.

Multifilament polyester yarn which develops high frequency crimp under load and is substantially free of twist liveliness is in great demand especially for singleand double-knit fabric constructions.

The present invention provides a new process, suitable for operation at yarn speeds 2,500 to 3,500 yards per minute or more, for producing textured polyester yarn. Preferred multifilament yarn embodiments are provided which have a crimp development of at least percent under 0.5 milligram per denier load and are free from twist liveliness. The filaments typically develop a crimp under 0.5 milligram per denier load which averages at least 30 crimps per extended filament inch. Other advantages of the invention will become apparent from the disclosure.

SUMMARY OF THE INVENTION In accordance with the present invention, drawn filaments of a polyester composition are'passed at high speed in frictional contact with an unheated nonmetallic pin for a distance of 0.5 to millimeters with a tension change over the pin of 0.2 to 1.5 grams per denier to modify the filaments frictionally on pin-contacting sides in a substantially continuous manner. By substantially continuous is meant that the lengths of discontinuities in the modified portion which are more than 2 millimeters long have a total value which is less than 5 percent of the filament length. The modified filaments are then fed at high speed into a jetted stream of compressible fluid heated to a temperature which will plasticize the filaments without causing fusion between filaments, forwarded in the stream, impinged in a plasticized condition on a moving surface such as a screen to separate them from the heated fluid, conveyed in an accumulated configuration on the moving surface for cooling in a substantially tensionless state, and finally taken up from the moving surface.

The yarn in its accumulated configuration on the moving surface contains polyester filaments which have a random, three-dimensional, curvilinear crimp along their lengths, with randomly varying crimp configuration along different filaments. The multifilament yarn can be taken up from the moving surface and then wound up taut on a bobbin or the like under considerable tension. Thus it is possible to form a tightly wound, dense package. Surprisingly, this does not destroy the ability of the yarn to become highly crimped when it is subsequently removed and heated under a 0.5 mg./den. load. In the crimped filament, the surface of the portion modified by passage over the pin is marked and closely spaced ripples that extend transversely to the filament length. The ripples can be readily seen when the filament is viewed at high magnification in a scanning electron microscope. The modified portion can be detected by a difference in refractive index from the remainder of the filament, as seen by interference microscopy. In general, the modified portion occupies from 3 to 20 percent of representative cross-sectional areas along the filament and is l to 3 microns in thickness, measured from the modified surface. The modified portion is substantially continuous along the filament lengths, as indicated above. In addition, the average length of discontinuities is usually less than 2 millimeters and the number of discontinuities longer than 2 mm. is usually less than 30 percent of the total.

The filaments preferably have an average crimp frequency of 30 to crimps per extended inch of filament after heating for 5 minutes in C. air under a load of 0.5 milligram per denier as described subsequently. Preferred textured multifilament yarns are composed of l to 6 denier filaments consisting essentially of polyethylene terephthalate and have a crimp development of 10 to 45 percent under 0.5 milligram per denier load. The textured yarns are free from twistliveliness. Those having a total denier of 70 to 250 are most useful in knit fabrics for dresses and suits.

The texturing process is generally operated at speeds of at least 900, preferably at least 2,500 yards per minute (ypm), with speeds greater than 3,500 ypm being possible. Preferably the filaments are in contact with the pin for a distance of l to 10 millimeters under conditions such that the filament tension just after the pin is between I and 4 grams per denier and this tension is 0.4 to 1.1 grams per denier greater than thetension just before the pin. The yarn must be drawn before it contacts the pin and preferably has been drawn so as to have 5 to 25 percent boil-off shrinkage. If desired, the pin-treatment step can follow the drawing step, sequentially, in a coupled two-step process.

In the pin-texturing step of the present invention, the yarn is passed over an unheated pin of nonmetallic ma terial, and frictional work exclusively, generated by the pin-filament contact and kept at the treatment site by the low conductivity of the pin, is used to modify the filaments. Thus, the process favors the use of high speeds to generate frictional work. This is in sharp contrast to prior art processes which rely on maintenance of heat externally in a heated wire or the like and trans fer of this heat to the filaments passing in contact with the wire; such processes characteristically suffer from nonuniformities in the filaments due to cooling of the hot wire by passage of the filaments over it, and obviously favor slow speeds to permit the filaments to take up heat from the wire.

In the present invention, the desired pin-filament contact distance of 0.5 to 15 mm. is obtained by appropriate selection of the pin diameter (e.g., 3/16 to inch) and wrap-angle (e.g., 30 to 90). The term pin includes curved surfaces which supply the above conditions. Obviously, sharp edges are to be avoided. Ceramic or like low-conductivity materials are preferred for the pin or curved surface.

The pin-treatment and jet-screen treatment steps are preferably coupled so that the filaments are modified and fed to the jetted stream of heated compressible fluid in a continuous process. The compressible fluid is jetted at sufficient pressure and temperature to form a stream which will forward and plasticize the filaments to impinge the filaments on the moving surface at high speed in a plasticized condition. In general, the fluid is supplied to a jet device at a pressure of 15 to pounds per square inch gauge and a temperature of 150 to 500C., and is jetted from one or more jet orifices. One skilled in the jet treatment art can readily select jet devices, pressures and temperatures which are suitable for treating particular yarns at desired yarn velocities.

The, plasticized filaments are preferably separated from the jetted stream by impingement on a moving screen, so that the filaments are deposited on the screen and the heated fluid passes through the screen. The screen is moving at a speed which will separate the filaments from the heated fluid in a crimped condition and allow adequate cooling time to set the crimp before the filaments are removed from the screen. A screen speed of 2 to 300 yards per minute is usually used.

The process is suitable for crimping multifilament yarn composed of any of the single synthetic linear polyester compositions conventionally used in textile filaments and yarns. Preferably, the polyester consists essentially of poly(ethylene terephthalate), which may be copolymerized with minor amounts of other components to improve textile properties; such copolyesters include poly(ethylene terephthalate/isophthalate), poly(ethylene terephthalate/adipate) and poly[ethylene terephthalate/S-(sodium sulfo)isophthalate]. Other polyesters include poly(tetramethylene terephthalate) and poly( l,4-cyclohexylene-dimethyleneterephthalate). The single composition may comprise intimate mixtures of the polyesters and/or copolyesters and may contain minor amounts of other additives (e.g., delusterants, antistatic agents, or other monomeric or polymeric additives).

Filaments having substantially round cross sections are preferred, but the products may have filaments of any other cross-sectional configuration, e.g., trilobal.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic representation of process and apparatus for continuously melt-spinning, drawing, and pin-texturing to produce filaments with latent crimp.

FIG. 2 is a schematic representation of process and apparatus for jet-screen-treating of previously pintextured filaments.

FIG. 3 is a schematic representation of a fully coupled, spinning, drawing, pin-texturing, and jet-screentreating process and apparatus for continuously producing yarn in accordance with the present invention.

FIG. 4 is a greatly enlarged cross-sectional view of one of the filaments of the yarns of this invention, the modified portion being indicated by cross-hatching.

FIG. 5 is a photomicrograph showing the rippled surface of one of the filaments of the final yarn of Example 3.

FIG. 6 is a side view of a filament of Example 3 at low magnification (about X) to illustrate crimps (indicated by arrows) counted in determining crimp frequency. The filament is viewed in a tensionless state.

FIGS. 7A-7D are magnified views showing (A) untextured, (B) pin-textured, (C) pin-textured/jet-screentreated, and (D) jet-screen-treated yarns, for comparative purposes as discussed in Example 2. The views show the yarns after they have been tested for crimp development under load, then removed from the skein and photographed in a tensionless state.

FIG. 8 is a magnified view showing the pin-textured/- jet-screen-treated yarn of Example 3. The view shows the yarn after it has been treated for crimp development under load, then removed from the skein and photographed in a tensionless state.

FIG. 9 is a cross-sectional plan view of the yarn passageway, treatment chamber and fluid conduits of the jet device used in Examples 1 to 4.

PROCESS EMBODIMENTS The products can be produced in a split operation illustrated in FIGS. 1 and 2 or in a completely continuous operation as illustrated in FIG. 3.

In FIG. 1, filaments 10 are melt-spun from spinneret 1 l, cooled, passed around feed rolls 12, through steam draw jet 13, over a finish-applying roll 14 and then around draw rolls 15 which have a considerably higher surface speed than the feed rolls to draw the yarn. The draw rolls may be located in a draw box to maintain a particular temperature, as desired. A traversing mechanism 16 is provided for guiding the filaments onto the draw rolls; when activated it varies the path of the drawn filaments on the rolls and over pin I7. The drawn filaments pass over texturing pin 17 with a change of direction 6, and pass around pulling rolls I8 which provide tension over the texturing pin. If desired, the filaments can be guided to the texturing pin by an adjustable idler roll (not shown) to facilitate changing the wrap angle 6 at the texturing pin in order to increase or decrease the length of pin-filament contact. The filaments pass from the pulling rolls over a postdraw finish-roll 19 to windup 20, which cross-winds the product under a tension that is best measured shortly after the post-draw finish-roll.

The filaments, having latent crimp imparted by the pin-treatment, can then be subjected to jet-screentreatment as illustrated in FIG. 2. The yarn 21 from feed package 22 is passed over ring guides 23 through pigtail guide 24 over feed rolls 25 in hot chest 26, to heat the yarn, as desired. The yarn then passes to ajet device 27, which may be one of the known devices for jet-bulking conventional untreated polyethylene terephthalate yarn with heated compressible fluid.

The jet device used in Examples 1 to 4 is of the type disclosed in Coon U.S. Pat. No. 3,525,134, and has the internal configuration illustrated herein in FIG. 9. The jet device used in each example comprises a longitudinal yarn passage terminating in a short length 12 having a width di of 0.033 inch and a depth of 0.030 inch; a throat region 13 having a width dt of 0.045 inch; an expanding treatment chamber 14 whose sides diverge at an angle B of 4.5 from the throat region to a width de of 0.22 inch at the chamber exit; and dual fluid conduits 7 and 8, each having a width do of 0.025 inch, disposed on either side of the yarn passage and intersecting the throat region at an angle a of 30. The dual fluid conduits and the yarn treatment chamber have the same depth of 0.060 inch.

The heated compressible fluid supplied to the jet device forwards the yarn through the treatment chamber, plasticizes it and propels it against a screen surface on rotating drum 28. The plasticized yarn is impacted on the hard wires of the screen and is permitted to remain on the screen in an accumulated configuration as indicated at Y on FIG. 2 until it reaches point 29 on the drum. The yarn is removed from the drum, passed over idler roll 30 to let-down rolls 31 over pigtail guide 32 to windup 33.

In the completely coupled process shown in FIG. 3, the filaments are spun and drawn as described for FIG.

1 and then pass from the draw rolls about pin 40, with change of direction 0, to pulling rolls 41 which provide tension on the yarn over the texturing pin. From 41, the filaments pass through heating jet 42, which serves to heat the filaments as desired, and then through bulking jet 43. The jet used can be of the type described above. Jet 43 is supplied with fluid under pressure and temperature which plasticizes the filaments. The filaments and fluid are propelled from the jet against screen-surfaced drum 44, which may be connected to a vacuum source to remove the fluid. The filaments are accumulated on the drum until removed therefrom at point 45. They then pass over pulling rolls 46, to finish roll 47 where finish is applied, if desired, and then to a suitable windup 48.

EVALUATION PROCEDURES Average-Crimp-Frequency Developed Under mg./den. Load The denier is determined using a yarn specimen having a length of 27 cm. under a tension which is merely sufficient to straighten the crimp, usually 0.1 gpd. This piece of yarn is used for the crimp frequency determination. A weight equal to 0.5 mg./den. (yarn denier times 0.0005 g.) is attached to one end of the yarn. Masking tape can be used to form the weight. The free end of the yarn is then attached to a suitable clip and the yarn is placed so as to hang freely, with the weight attached to the bottom end, in a 120C. air oven for 5 minutes. it is then removed and permitted to cool, relaxed, on a velvet-covered board for at least 5 minutes. Ten filaments are separated from the yarn, carefully, without stretching. Masking tape or the like is used to attach the filament at top and bottom to a clear, plastic straight-edge, so that the filament is in a relaxed condition on the straight-edge. Using a Shadowgraph (See FIG. 6) and about 20X magnification, the number of crimps (C at 0.5 mg./den.) in the segment of filament between the two attachment points is counted. The extended length of this same segment of filament is measured under a load sufficient to straighten but not stretch the segment, e.g., a 0.6 g. weight for 2 to 6 dpf filaments. This is done by attaching one end of the filament at the top to a vertical straight-edge, permitting it to hang freely, tensioned by the weight, taping it to the straight-edge and measuring the extended length in inches (L of the segment. Crimp frequency in crimps per inch (cpi) is calculated using the formula:

cpi C at 0.5 mg./den./L

Crimp frequency for each of the 10 filaments is determined in this way and the average of the 10 values is reported as Average Filament Crimp Frequency in crimps per extended inch of filament. Crimp Development Under 0.5 mg./den. Load The denier is determined on yarn which is ready for knitting. For denier measurements, yarn length is determined under a 0.1 gpd load. A 3,000-denier skein is prepared from the yarn, the number of wraps in the skein being determined by dividing 1,500 by the yarn denier. The skein is suspended from a hook and a 1.5- gram load (0.5 mg. per denier) is attached to the bottom of the skein loop; this weight remains attached during all the remaining measurements and steps of the test. Next, a SOD-gram weight (100 mg./den.) is attached to the skein (also at the bottom) and is then removed; this is done three times to exercise the skein.

The 300-gram weight is attached again, kept on the skein for 5 i 1 seconds, and removed. The skein is then hung in an oven at 120C. for 5 i 1 minutes, removed, hung from a hook on a skein-measuring device, and permitted to cool at room temperature for 5 minutes. Skein length [measured on the skein between the hook and the 1.5 g (0.5 mg./den.) weight] is recorded as L05. Finally, a 300-gram load mg./den.) is attached and kept on the skein for 5 i 1 seconds and skein length is again measured and recorded as L The percent crimp development under 0.5 mg./d. load is then calculated using the following formula:

l( 100 0.5)/ l00] X 100 Photomicrographs of Filament Surfaces A scanning electron microscope (SEM) is used to study the nature of the abraded surface of the filaments. A short sample (about %-inch long) of yarn is mounted on a standard Stereoscan stub (%-inch diameter aluminum stub). Two strips (As-inch X A-inch) of double-faced adhesive tape are fixed /2-inch apart and parallel to each other on the stub surface. The sample of yarn is lightly teased to separate the filaments, and each yarn end is fixed to one strip of the adhesive. When mounting crimped yarn, no tension is applied so that the yarn is mounted with its crimp undisturbed. Silver circuit paint is dabbed on both ends of all filaments and on the adhesive tape to insure electrical continuity to the specimen stub. The final step of specimen preparation involves the vacuum evaporation of 60/40 Au/Pd coating onto the surface of the sample and stub which insures electrical continuity over the entire stub. The thickness of this coating is estimated to be of the order of 300-400 A which is below the level of resolution of the SEM used; thus, the coating is not seen when viewing filaments by this technique.

The stub is placed in the specimen holder and after evacuation of the specimen chamber, the specimen is viewed in the, SEM. Typical viewing conditions are 20KV electrons with a beam current of 200 t-amps, and a specimen tilt of 30 relative to the impinging electron beam. After areas of the filaments exhibiting modified surfaces are located, micrographs are recorded at, e.g., 200, 500, 1,000 and 2,000 X magnification. This series of magnifications includes a sufficiently low magnification to illustrate the position of the modified surface relative to the crimp and a sufficiently high magnification to reveal details of the modified surface.

When viewed by this technique, unrelaxed pintextured filaments exhibit a frictionally modified surface running along the filament length; in the relaxed filaments this surface can be seen to have a plurality of ripples which are visible on the abraded surface and run transversely with respect to the filament length. lt is generally on the outside of crimp bends.

Continuity of the Modified Portion Interference microscopy is used to determine the continuity of the modified portion along filament length L, where L is taken as 40 mm., times the number of filaments in the yarn for any yarn having 34 filaments. For other yarn counts, a total of 1,360 mm., distributed uniformly across the yarn, is viewed.

A 40-mm. length is cut from the yarn. The individual filaments (typically 34 filaments) are separated. Each 40-mm. long filament is mounted on a glass slide and immersed in Refractive lndex Fluid of an index of refraction (N) which matches the index of refraction (N perpendicular) of the unmodified portion of the filament for light vibrating perpendicular to the fiber axis, e.g., a fluid of N 1.540 is used for poly(ethylene terephthalate). The filament, after immersion in the fluid, is then covered with a second glass slide and the assembly is placed on the stage of the interference microscope. Using a suitable device, the assembly is advanced across the viewing area so that the entire 40- mm. length is viewed at 200X.

The presence of a modified portion is detected by interference contrast (i.e., the modified portion will be of different color than the remainder of the filament) or by fringe field (i.e., a fringe shift indicates a change in index of refraction going from modified to unmodified areas of the filament). Once a modified portion is detected, its path is followed along the filament length and the number and length of all discontinuities in its path are recorded. For convenience, a calibrated eyepiece, such that at 200X each division on the eyepiece equals pt, is used and the length of the discontinuities is reported in divisions and later converted to mm. by the formula:

mm. [(number of divisions)/(1000)] X 5 The following are determined: M total number of all discontinuities N number of discontinuities greater than 2 mm (2 mm. 400 divisions) U sum of lengths of all discontinuities, expressed in mm. V= sum of the lengths of discontinuities greater than 2 mm., expressed in mm. L total filament length viewed, i.e., 40 mm X the number of filaments viewed. From these values, the following are calculated: Average length of all discontinuities U/M percent of long 2 mm.) discontinuities N/M X 100. percent of filament length occupied by long 2 mm.) discontinuities V/L X 100. Dimensions of Modified Portion: Cross-Sectional Views A cross section of the yarn sample is suitably prepared for microtome sectioning, e.g., a yarn bundle is mounted in a Beem capsule and embedded with epoxy (Maraset from Marblette Corp.) After trimming the cured stub, sections which are approximately 6 microns thick are obtained using a rotary microtome (Spencer Model 860) with a steel blade. Sections are placed onto the two halves of a cut microscope slide (insures contant thickness for a two-beam Leitz Transmission lnterference Microscope). The two specimen slides are completed by immersing the sections in refractive index oil (Cargille Index of Refraction Fluid N 1.530) and covering with microscope cover slips. One specimen slide is placed onto the reference beam stage and the other slide is placed onto the sample beam stage of the two-beam Leitz Transmission Interference Microscope. The specimen section is viewed at 500X magnification. Following the alignment procedures, the fringe field is obtained in the field of view in white light. The fringes are then fluffed out to obtain interference contrast, i.e., the fringes are taken to their maximum separation. The specimen section is brought into sharp focus and the index variation across the textured filaments cross section is recorded on color film as the retardation or color difference across the filament section. The procedure can be carried out in monochromatic illumination and recorded on black and white film. The procedure described above is performed without the analyzer in the optical system and is used as a qualitative detection technique for presence of the modified portion of different refractive index. Micrographs obtained in this way will show the modified portion in one color as indicated by crosshatching in FIG. 4 and the remainder of the filament in another color.

Thickness of the modified portion is determined from 1,000X micrographs of cross sections by measuring the thickness of the portion (cross-hatched region, referring to FIG. 4) on three cross sections at three points each, and averaging the nine values. A small plastic ruler is most conveniently used, and 1 mm. 1 u.

Percent area of the modified portion is determined by making Xerox copies of the 1,000X micrographs, cutting out 8-12 cross sections from the copies, and weighing the filament cross section copies before (W,,) and after W cutting the modified portion therefrom. Percent Area W -W IW X 100, where W,, and W, are total weights in grams, before and after cutting.

specific ILLUSTRATIONS Example 1 This example illustrates a split process for producing the yarn of the present invention.

Poly(ethylene terephthalate) yarn of 34 filaments is melt-spun, drawn, and then passed over an unheated pm as shown in FIG. 1, using the specific process conditions given in Table l. The yarn is then treated to impart a random curvilinear crimp, using the apparatus of FIG. 2 and the specific process conditions of Table 2.

The final yarn is converted to a Swiss Pique double knit fabric by knitting to a greige weight of 6 oz./yd. The fabric is tumble-relaxed in a Cissell Dryer and then scoured and dyed with blue dye in a jet pressure dyer. After an after-scour and drying, the knit fabric is stretched to about 60-inch width and heat-set as is customarily done for commercial knits. The fabric bulk (cc/g.) is then determined by dividing the fabric thickness (cm.) (measured at 5 g./cm. pressure over an area of 16.9 in?) by the fabric unit weight (g./cm.

Properties of the yarn and fabric bulk data are given in Table 4. The fabric constructed from yarn crimped by combining pin treatment with jet-screen-treatment shows excellent stitch clarity and dye depth, with no objectionable glitter.

Example 2 In this example the results obtained when commercial drawn yarn is pin-textured and jet-screen-treated are compared with the results obtained with either treatment alone.

The feed yarn is commercially available semi-dull, poly(ethylene terephthalate) yarn of denier and 34 filaments of round cross-section, the yarn having been previously drawn about 4X and having a residual shrinkage on boil-off of about 10 percent. The yarn is removed from its bobbin, passed through a tension gate and over a roller to a pair of feed rolls, then over an unheated pin at wrap angle 0 to a pair of stretch rolls and then over a finish-applying roll to a suitable windup. Specific process details are given below:

Feed Rolls Speed (YPM) 1001 Wraps 4 Stretch Rolls Speed (YPM) I052 Wraps 4 Stretch 5 Pin Details Type Glass Rod Size (Diameter in inches) 5/16 Yam Wrap Angle 66 Pin-Filament Contact Length (mm) 4.6 Tension Before Pin (gpd) 0.7 Tension After Pin (gP 1.7 Tension Change (gpd) l Windup Speed (YPM) 1035 Pin-Textured Yarn Count (den-fil) 150-34 The pin-textured yarn is then jet-screen-treated using the apparatus of FIG. 2 and the specific conditions in Properties of the yarn are given in Table 4. FIG. 8 shows a portion of the yarn at the indicated magnification.

Example 4 This example illustrates a split process for texturing 70-denier, 34-filament polyester yarn.

The feed yarn is commercially available, poly(ethylene terephthalate) semi-dull yarn of 70 denier and 34 filaments, of round cross-section, the yarn having been previously drawn about 4X and having a residual shrinkage on boil-off of about 10 percent. The yarn is removed from its bobbin, passed through a tension gate and over a roller to a pair of feed. rolls, then over an unheated pin at wrap angle 0 to a pair of stretch rolls and then to a suitable windup. Specific process details are given below:

velopment under 0.5 mg./den. load than the other yarns. Lawson single-knit tubings, from yarns which have received the complete treatment (pin texturing followed by jet-screen-treatment) have a firmer, bulkier hand than similar fabrics prepared from untreated yarn or yarns given only a single-texturing treatment.

Yarn of the present invention (7C) is also converted to an interlock double-knit fabric on an l8-cut F ouquet knitting machine. After knitting to a boiled-off weight of 8.2 oz./yd. the fabric is tumble-relaxed at 200F.

for minutes in a Cissell Dryer, scoured, and dyed in an 18-inch beck at the boil with blue dye. Following an after-scour and drying, the fabric is stretched to about 60-inch-width and heat-set at 320F. for seconds at 15 percent overfeed. Bulk is measured by dividing fabric thickness in centimeters (measured at 5 g./cm. pressure over an area of about 7 cm?) by the fabric unit weight in grams per square centimeter. Results are given in Table 4.

Example 3 This example illustrates a completely coupled process wherein yarn is spun, drawn, pin-treated and jetscreen-treated continuously.

The yarn is prepared using the apparatus shown in FIG. 3 and the process conditions given in Table 3.

Table 2. The final yarn is then tested for crimp develop- 20 Feed Rolls ment under 0.5 mg./den. load and is compared with Speed (YPM) 900 other similarly tested yarns in FIG. 7 (which shows por- Stretch l 4 tions of yarn at the indicated magnification) and in the (YPM) 945 Table below as follows: grsatpst h g re C FIG. 7A Feed yarn no texturing treatment. 25 Denier Teaming Pin 7B Feed yarn, which has been pin-textured only, Pin Details using conditions in above Table. gyp t h 7C Feed yarn, which has been pin-textured as fg ig g 15,2 59 above, and then et-screen-treated as 1n Table 2. Pin-filament Contact Length 7D Feed yarn, which has been jet-screen-treated 30 $22, Before Pin mm) M only, uslng cond1t1ons as in Table 2. Tension After Pi (gp L5 Crimp Development Crimp-Frequency (cpi) Yarn Denler Under 0.5 mgJden. Load Under 0.5 mgJden. Load 7A 0.7 nil. 7B 151 1.3 6 7c -190 11.9 31 7D 185 5.6 25

o v I As can be seen from above, the yarn accordlng to the w, d S z g figw ge (gpd) g151 v ion s m rkedl hi h r rim de- I present m ent (7C) ha a y g e c p Pin-Textured Yarn Count (den-fil) 70-34 This yarn is then jet-screen-treated using the apparatus of FIG. 2 and the specific process conditions in Table 2. Final yarn denier is 90.

The yarn is suitable for, single weft knit as well as warp knit fabrics and for woven fabrics. In Table 4, yarn properties and bulk data for a single-knit jersey of the pin-textured/jet-screen-treated yarn of this Example are given.

Example 5 This example illustrates a split process using steam in the jet-screen-treatment step.

Poly(ethylene terephthalate) yarn of 34 filaments is melt-spun, drawn, and then passed over an unheated pin as shown in FIG. 1, using the specific process conditions given in Table l.

The yarn is then treated to impart a random curvilinear crimp, using the specific process conditions given for Example 5 in Table 2. The yarn is fed through a jet device and impacted on a screen drum as shown in FIG 2.

The jet used is of the type described in Yngve, U.S. Pat. No. 3,638,291. Referring to FIG. 2 of the Yngve patent, the dimensions of the jet are as follows:

Internal Supply Manifold 22 (dia. in inches) 0.189

Lateral Separation between Manifolds 22 (center-to-center distance in inches) 0.625 Angularly Disposed Conduits 24, 26

(width in inches) 0.039 (depth in inches) 0.060 lncluded Angle between Conduits 24 and 26 (degrees) 60 Yarn Passage Section 34 (length in inches) 0.202 (width in inches) 0.043 (depth in inches) 0.030 Enlarged Throat Region 36 (vertical length in inches) 0.159 (depth in inches) 0.060 Opening 37 (width in inches) 0.143 (depth in inches) 0.060 Triangular-Shaped Expansion Cavity 38 (vertical height in inches) 0.250 (maximum width in inches) 0.604 (depth in inches) 0.060 Opening 39 (width in inches) 0.104 (depth in inches) 0.060 Continuously Expanding Treatment Chamber 40 (width of Exit 42 in inches) 0200 (length from 39 to 42 in inches) 0.923

The heated fluid supplied to the jet is superheated steam (315C., 29 psig). The plasticized yarn is impacted on the screen and, while still in an accumulated configuration on the screen, is quenched by spraying a mist of cold tap water against the yarn so that the yarn is cooled in a substantially tensionless state. The yarn is then taken up from drum 28, passed to let-down rolls 31 at 810 ypm and then to a set of tensioning rolls (not shown) at 870 ypm, and finally to windup 33. Tension on the yarn at windup is 15-20 grams (6.9 9.3 gpd). Properties of the yarn are given in Table 4.

Example 6 This example illustrates a process wherein yarn is spun and drawn in one step, subjected to additional drawing and pin-textured in another step, and then jetscreen-treated using steam in the jet.

Poly(ethylene terephthalate) flake is used which contains 0.05 percent TiO and has a relative viscosity of 30 measured at 25C. using a concentration of 2.15 grams of polymer in 20 ml. of fomal (10 parts by weight phenol to 7 parts by weight 2,4,6-trichlorophenol; density of 1.232 t 0.001 g/cc). Prior to viscosity measurement, the polymer is dissolved by heating the mixture to 140C. for 30 minutes.

The polymer is melt-spun using conventional equipment an using a spin-pack-block temperature of 292C. and a spinneret having 34 holes, each of 0.0l-inch diameter and 0.030-inch length. The freshly spun filaments are cooled, passed over a finish roll, then passed around feed rolls rotating at 561 ypm. Yarn denier at this point is 590. From the feed rolls the yarn is passed through a 4-inch long steam-draw-jet operating with steam at 220C. and 80 psig pressure, and then to draw rolls (2,495 ypm, room temperature). Draw ratio is 4.45X. The drawn yarn is passed to 2 sets of let-down rolls 2,495 and 2470-2496 ypm respectively), over a finish roll, and is then wound up at 2,422-2,430 ypm.

The yarn is then further drawn (l.l4X) by passing it to a set of feed-rolls (8-9 wraps, 1,140 ypm), then through a steam-draw-pipe (3/8-inch diameter, 9.5- inch length, supplied with atmospheric steam at 100C.), to a set of draw-rolls (7-8 wraps, 1,300 ypm). Yarn tension, measured with a Schmidt- Waldkraiburg device just prior to passage over the draw-rolls, is 190-200 grams.

Yarn from the last draw roll (final wrap) is led over a three-eighths-inch diameter AlSiMag texturing pin with a change of direction 0 of 90, then passed to a set of take-up rolls (1,302 ypm, 6-8 wraps) and wound up.

The pin-textured yarn is jet-screen-treated using the conditions listed for Example 6 in Table 2. The yarn is fed through ajet device and impacted on a screen drum as shown in FIG. 2. The jet used, and its specific dimensions, are the same as in Example 5. The heated fluid supplied to the jet is superheated steam (315 t 5C., 29 psig). The plasticized yarn is impacted on the screen and, while in an accumulated configuration on the screen, is quenched by spraying a mist of cold, tap water on the yarn at point Y, referring to FIG. 2. The yarn is then taken up from drum 28, passed to let-down rolls 31 at 933 ypm and then to a set of tensioning rolls (not shown) at 1,000 ypm, and finally to windup 33.

Properties of the final bulked yarn are given in Table 4 and additional properties are given for the yarn at various stages of processing in Table 5.

Estimated Yarn Temp. same as draw box (immediately before contacting pin) Denier at texturing pin 141 Pin Details Type White AlSiMag Size (inches) 3/8 X 2% Yarn wrap angle 60 Tension before pin (gpd) 0.8 Tension after pin (gpd) 1.2 Tension change (gpd) 0.4 Pin-filament contact (mm) 5 Pulling Roll Conditions Counter reading 4410 Speed, rpm 8820 Speed, ypm 2937 Wraps 2% Stretch (draw roll to 5% pulling roll) windup Conditions Counter 4487 Speed, ypm 2874 Tension (gpd) 0.4

Measured at a concentration of 8 grams of polymer in ml. of hexafluoroisopropanol solution containing 100 parts per million of 11,50 at 25C.

TABLE 2 Feed Rolls Ex. 1 Ex. 2 Ex. 4 Ex. 5 Ex. 6

Speed (ypm) 3000 3000 3000 1400 1450 Wraps I0 10 10 1 l 1 1 Temp. (C.) 125 125 I80 Bulking Conditions TABLE 2- Continued Feed Rolls Ex. 1 Ex. 2 Ex. 4 Ex. 5 Ex. 6

Jet Used FIG. 9 H6. 9 F16. 9 i Fluid Used Air Air Air Steam Steam Fluid Temp. (C.) 335 375 305 315 315 Pressure (psig) 100 110 82 29 29 mm Screen Mesh I 40 40 4O 40 40 Distance from Jet (inches) 7 0.050 0.050 0.050 0.125 0125 Vacuum (in. 11 0) 4.5 Circumferential Speed (fpm) 700 270 270 21-30 21-30 Yam Residence Time on Drum (min.) 0.002 0.004 0.004 Yarn Residence Length (Jet to Take-Off) on drum (inches) 12 12 l2 l2 Overfeed (Feed to Drum) 1186 3230 3230 13900- 14400- 19900 20614 M1391 Speed (ypm) 2200 2300 2180 810 933 Wraps 3% 3% 3% 6 6 Overfeed" (Feed Rolls to Let-Down Rolls) 36 30 38 73 55 M WinduP (g/ 0.11 0.05 0.1

"k Overfeed High speed-low speed/Low speed (100) "See Example for further details TABLE 3 TABLE 3-Contmued A t Stretch (draw roll to pulling roll) 4 Yarn Type Heating Jet Polymer Type Poly(ethylene Fluid air terephthalate) Temperature (C.) 300 Relative viscosity 22 Pressure (p ig) TiO, 0.3 Feed filament cross section round w No. of filaments 34 30 Jet Used FIG 9 Fluid Used Air Temperature (C.) 468 Speed, rpm 1912 Pressure (psig) 90 Speed, ypm 667 Wraps 2 /2 Relaxing Drum Screen mesh 46 m 35 Vacuum (in. mo) 24 .let temperature (C.) I 225 Circumferential Speed (fpm) 326 Jet pressure (psig) 85 Yarn Residence Length on Drum (ft.) 0.9-1.2 Draw ratio 4.2X

Pulling Rolls (FIG. 3, 46) MM Yarn tension before rolls (gpd) 0.06 Speed, rpm 4205 Counter 3180 Speed, ypm 2801 Wraps 4 Wraps 6 Speed (yp 2080 Draw Box Temperature (C.) 108 Yarn tension after rolls (gpd) 0.1 Denier at texturing pin 121 Overfeed (Feed Rolls to the Pulling Rolls 46) 40 Pi D il Denier Overfeed (final Den. minus feed- Type whim AlsiMag roll denier T feed-roll denler X 100) 34 Size (inches) Yarn wrap angle (degrees) M Tension before pin (gpd) 0.7 Speed (ypm) 2161 Tension after Pi (gp 1.4 Yarn tension (gpd) 0.14 Tension change (81 d) 0.7 Pin-Filament contact (mm) 5.8 M Yarn Temperature (3 inches after 50 Tenacity (gpd) 3.49 pin) ("C.) 70.5 Elongation 51.3 Modulus (gpd) 39.3 2% p p 2910 Measured at a concentration 01' 8 grams of polymer in ml. of Wraps 4 hexafluoroisopropanol solution containing 100 parts per million of H,SO.. at 25C.

TABLE 4 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6

Final Yarn Denier* 185 185-190 168 90 216 -167 Filaments 34 34 34 34 34 34 Crimp Development (0.5 mgJden.) 16 12-13 13 17 39 37 Average Crimp Frequency (cpi) 33 31 30 48 41 46 Thickness of Modified Portion (p) 2.1 2.6 1.4 1.4 1.7 1.5 Cross Section Occupied by Modified Portion 5.9 14 5.1 6.7 3.9 3.5 Long Discontinuities 2 mm) 0 11 0 3.9 0 9.4 Average Length of All Discontinuities (mm) 1.04 1.21 1.2 0.79 0.58 1.12

% Fil. Length Occupied by Long 2 mm) Discontinuities 0 4 0 0.6 0 2.0

ABLE 4-C0ntinued Ex. I Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6

Double-Knit Fabric: Type Swiss lnter- Single- Pique lock Knit Jersey Weight (oz/yd?) 7.2 7.1 3.7 Bulk cc/g.) 4.1 3.6 4.9

As measured for crimp tests TABLE 5 is between 1 and 4 grams per denier and this tension is 0.4 to 1.1 grams per denier greater than the tension just Y F After Asfter before the pin.

arn rom Pin- Jetcreen Property Last Draw Roll Texturing Treatment process as defined m clalm. l said yam filaments contact said nonmetallic pm at a speed of D enier 153 126 155-167 2,500 to 3,500 yards per minute. i-gg' fi' i 4 34 34 6. A process as defined in claim 1 wherein the fila- (gpd)* 4.9 4.8 3.1 ments are modified and fed to said jetted stream of Elongation l4.3 16.2 43 Initial Modulus heated compressible fluid m a continuous coupled pro (gpdl 143 I26 48 CeSS- I Denslly -l L372 L394 7. A process as defined in claim 1 wherein said com- Dclermincd in accordance with ASTM D-225669 Determined in accordance with ASTM D-l505 We claim:

1. In the process of preparing multifilament yarn of filaments which crimp due to asymmetric shrinkage properties when heat-relaxed, wherein said asymmetric shrinkage properties are imparted by passing the filaments under tension in contact with a hard surface to modify the filaments along their lengths; the improvements for providing better crimping properties in polyester yarn and higher processing speeds, wherein the improvements comprise passing drawn filaments of a single polyester composition at high speed in frictional contact with an unheated nonmetallic pin for a distance of 0.5 to 15 millimeters at a tension change over the pin of 0.2 to 1.5 grams per denier to modify the filaments substantially continuously on pin-contacting sides, the sum of the lengths of discontinuities in the modified portion which are more than 2 millimeters long being less than 5 percent of the filament length, and then imparting a random three-dimensional, curvilinear, configuration continuously along the modified filaments by (a) feeding the filaments at high speed into a jetted stream of compressible fluid heated to a temperature which will plasticize the filaments without causing fusion between filaments, and (b) impinging the filaments in a plasticized condition on a moving surface to separate the filaments from the heated fluid and convey the filaments on the moving surface for cooling in a substantially tensionless state.

2. A process as defined in claim 1 wherein said yarn has been drawn to have a boil-off shrinkage of 5 to percent before the yarn filaments are passed in contact with said nonmetallic pin.

3. A process as defined in claim 1 wherein said yarn filaments contact said nonmetallic pin at a speed of at least 900 yards per minute.

4. A process as defined in claim 3 wherein said filaments contact said nonmetallic pin for a distance of l to 10 millimeters, the filament tension just after the pin pressible fluid has a pressure of 15 to 150 pounds per square inch gauge and a temperature of 150 to 500C. when it is jetted.

8. A process as defined in claim 7 wherein the plasticized filaments are separated from said jetted stream on a moving screen.

9. A process as defined in claim 8 wherein said screen is moving at 2 to 300 yards per minute.

10. A process as defined in claim 1 wherein said polyester filaments consist essentially of poly(ethylene terephthalate).

11. A textured multifilament yarn of l to 6 denier filaments consisting essentially of a single poly( ethylene terephthalate) composition which are characterized by (a) a random three-dimensional, curvilinear crimp along the filament lengths with randomly varying crimp configuration along different filaments, (b) a frictionally modified minor portion of the filament crosssection extending along the filament lengths with a continuity such that less than 5 percent of the filament length is occupied by discontinuities longer than 2 millimeters, (c) the locations of said modified portions being marked on the filament surfaces by closely spaced parallel ripples that extend transversely to the filament length, and (d) an average crimp frequency of 30 to crimps per extended filament inch after heating for 5 minutes in C. air under 0.5 milligram per denier load; the multifilament yarn being characterized by a crimp development of 10 to 45 percent after heating for 5 minutes in 120C. air under 0.5 milligram per denier load, and by being free from twist liveliness.

12. A textured yarn as defined in claim 11 wherein said yarn has a total denier of 70 to 250.

13. A textured yarn as defined in claim 11 wherein said minor modified portion occupies 3 to 20 percent of the filament cross-section and is l to 3 microns in thickness.

14. A textured yarn as defined in claim 11 wherein said modified portion is generally located on filament sides which are on the outside of crimp bends. 

1. IN THE PROCESS OF PREPAING MULTIFILAMENT YARN OF FILAMENTS WHICH CRIMP DUE TO ASYMMETRIC SHRINKAGE PROPERTIES WHEN HEAT-RELAXED, WHEREIN SAID ASYMMETRIC SHRINKAGE PROPERTIES ARE IMPARTED BY PASSING THE FILAMENTS UNDER TENSION IN CONTACT WITH A HARD SURFACE TO MODIVY THE FILAMENTS ALONG THEIR LENGTHS; THE IMPROVEMENTS FOR PROVIDING BETTER CRIMPING PROPERTIES IN POLYESTER YARN AND HIGHER PROCESSING SPEEDS, WHEREIN THE IMPROVEMENTS COMPRISE PASSING DRAWN FILAMENTS OF A SINGLE POLYESTER COMPOSITION AT HIGH SPEED IN FRICTIONAL CONTACT WITH AN UNHEATED NONMETALLIC PIN FOR A DISTANCE OF 0.5 TO 15 MILLIMETERS AT A TENSION CHANGE OVER THE PIN OF 0.2 TO 1.5 GRAMS PER DENIER TO MODIFIY THE FILAMENTS SUBSTANTIALLY CONTINUOUSLY ON PIN-CONTACTING SIDES, THE SUM OF THE LENGTHS OF DISCONTINUTIES IN THE MODIFIED PORTION WHICH ARE MORE THAN 2 MILLIMETERS LONG BEING LESS THAN 5 PERCENT OF THE FILAMENTS LENGTH, AND THEN IMPARTING A RANDOM THREE-DIMENSIONAL, CURVILINEAR, CONFIGURATION CONTINOUSLY ALONG THE MODIFIED FILAMENTS BY (A) FEEDING THE FILAMENTS AT HIGH SPEED INTO A JETTED STREAM OF COMPRESSIBLE FLUID HEATED TO A TEMPERATURE WHICH WILL PLASTICIZE THE FILAMENTS WITHOUT CAUSING FUSION BETWEEN FILAMENTS, AND (B) IMPINGING THE FILAMENTS IN A PLASTICIZED CONDITION ON A MOVING SURFACE TO SEPARATE THE FILAMENTS FROM THE HEATED FLUID AND CONVEY THE FILAMENTS ON THE MOVING SURFACE FOR COOLING IN A SUBSTANTIALLY TENSIONLESS STATE.
 2. A process as defined in claim 1 wherein said yarn has been drawn to have a boil-off shrinkage of 5 to 25 percent before the yarn filaments are passed in contact with said nonmetallic pin.
 3. A process as defined in claim 1 wherein said yarn filaments contact said nonmetallic pin at a speed of at least 900 yards per minute.
 4. A process as defined in claim 3 wherein said filaments contact said nonmetallic pin for a distance of 1 to 10 millimeters, the filament tension just after the pin is between 1 and 4 grams per denier and this tension is 0.4 to 1.1 grams per denier greater than the tension just before the pin.
 5. A process as defined in claim 1 wherein said yarn filaments contact said nonmetallic pin at a speed of 2,500 to 3,500 yards per minute.
 6. A process as defined in claim 1 wherein the filaments are modified and fed to said jetted stream of heated compressible fluid in a continuous coupled process.
 7. A process as defined in claim 1 wherein said compressible fluid has a pressure of 15 to 150 pounds per square inch gauge and a temperature of 150* to 500*C. when it is jetted.
 8. A process as defined in claim 7 wherein the plasticized filaments are separated from said jetted stream on a moving screen.
 9. A process as defined in claim 8 wherein said screen is moving at 2 to 300 yards per minute.
 10. A process as defined in claim 1 wherein said polyester filaments consist essentially of poly(ethylene terephthalate).
 11. A textured multifilament yarn of 1 to 6 denier filaments consisting essentially of a single poly(ethylene terephthalate) composition which are characterized by (a) a random three-dimensional, curvilinear crimp along the filament lengths with randomly varying crimp configuration along different filaments, (b) a frictionally modified minor portion of the filament cross-section extending along the filament lengths with a continuity such that less than 5 percent of the filament length is occupied by discontinuities longer than 2 millimeters, (c) the locations of said modified portions being marked on the filament surfaces by closely spaced parallel ripples that extend transversely to the filament length, and (d) an average crimp frequency of 30 to 70 crimps per extended filament inch after heating for 5 minutes in 120*C. air under 0.5 milligram per denier load; the multifilament yarn being characterized by a crimp development of 10 to 45 percent after heating for 5 minutes in 120*C. air under 0.5 milligram per denier load, and by being free from twist liveliness.
 12. A textured yarn as defined in claim 11 wherein said yarn has a total denier of 70 to
 250. 13. A textured yarn as defined in claim 11 wheRein said minor modified portion occupies 3 to 20 percent of the filament cross-section and is 1 to 3 microns in thickness.
 14. A textured yarn as defined in claim 11 wherein said modified portion is generally located on filament sides which are on the outside of crimp bends. 